Class factory decorator pattern in TypeScript. Used for dependency injection in Express.

ts-classfactory.ts

export default function RouteController(decoratorParams:Object) {
    var providers:any[];

    if (Array.isArray(decoratorParams['providers'])) {
        providers = decoratorParams['providers'].map((provider:string) => {
            let p = require(provider);
            return p;
        });
    }

    return function(decoratedClass:any) {

        function wrapConstructor(app) {
            return new decoratedClass(app, ...providers);
        }

        wrapConstructor.prototype = decoratedClass.prototype;

        return <typeof decoratedClass> wrapConstructor;
    }
}